U.S. patent number 6,990,760 [Application Number 09/688,513] was granted by the patent office on 2006-01-31 for lip for an excavation bucket.
This patent grant is currently assigned to Caterpillar Sarl. Invention is credited to Schalk Willem Petrus Esterhuyse, Oswald Cornelius Dannhauser Zaayman.
United States Patent |
6,990,760 |
Zaayman , et al. |
January 31, 2006 |
Lip for an excavation bucket
Abstract
The invention relates to a lip for an excavation bucket. The lip
includes a lower plate defining a plurality of integral projections
along a front edge thereof, an upper plate and a central plate
sandwiched between the lower plate and the upper plate so as to
form a laminated structure. The upper plate also defines a
plurality of integral projections which together with the
projections on the lower plate form tool attachment formations in a
serrated front edge of the laminated structure for supporting
ground-engaging tools on the lip.
Inventors: |
Zaayman; Oswald Cornelius
Dannhauser (Pretoria, ZA), Esterhuyse; Schalk Willem
Petrus (Pretoria, ZA) |
Assignee: |
Caterpillar Sarl (Geneva,
CH)
|
Family
ID: |
35694687 |
Appl.
No.: |
09/688,513 |
Filed: |
September 14, 2000 |
Current U.S.
Class: |
37/446 |
Current CPC
Class: |
E02F
3/36 (20130101); E02F 3/40 (20130101); E02F
9/2883 (20130101) |
Current International
Class: |
E02F
3/36 (20060101) |
Field of
Search: |
;37/452,455,450,446,398,341,342,379,444,903 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Batson; Victor
Attorney, Agent or Firm: Kilpatrick Stockton
Claims
We claim:
1. A lip for an excavation bucket including a lower plate defining
a plurality of integral projections along a front edge thereof; an
upper plate joined to the lower plate so as to form a laminated
structure, the upper plate defining a plurality of integral
projections which, together with the projections on the lower
plate, form tool attachment formations in a serrated front edge of
the laminated structure for supporting ground-engaging tools on the
lip; at least one additional plate between the upper plate and the
lower plate; and the at least one additional plate projecting from
the upper and lower plates, between adjacent tool attachments
formations, for attaching shrouds to the lip.
2. A lip for an excavation bucket according to claim 1, wherein the
projections on the upper and lower plates are arranged so that the
tool attachment formations are inclined relative to the plane of
the lip.
3. A lip for an excavation bucket according to claim 1, wherein the
upper plate, the lower plate and the additional plate or plates are
fabricated from rolled steel plate and are subsequently welded
together.
4. A lip for an excavation bucket according to claim 1, wherein the
lip curves upwardly at each lateral end thereof.
5. An excavation bucket including a lip according to claim 1.
6. A lip for an excavation bucket according to claim 1, wherein the
additional plate defines openings along its length for reducing the
mass of the additional plate.
7. A lip for an excavation bucket including a lower plate defining
a plurality of integral projections along a front edge thereof, and
an upper plate joined to the lower plate so as to form a laminated
structure, the upper plate defining a plurality of integral
projections which, together with the projections on the lower
plate, form tool attachment formations in a serrated front edge of
the laminated structure for supporting ground-engaging tools on the
lip, at least one additional plate between the upper plate and the
lower plate, and wherein the additional plate or plates are
designed to project from the upper and lower plates between
adjacent tool attachment formations and include attachment
apertures for attaching shrouds to the lip.
8. A lip for an excavation bucket including a lower plate defining
a plurality of integral projections along a front edge thereof, and
an upper plate joined to the lower plate so as to form a laminated
structure, the upper plate defining a plurality of integral
projections which together with the projections on the lower plate
form tool attachment formations in a serrated front edge of the
laminated structure for supporting ground-engaging tools on the
lip, at least one additional plate between the upper plate and the
lower plate, and wherein the lip includes on additional plate
between the upper and lower plates, and the additional plate
defines openings along its length for reducing the mass of this
plate.
Description
BACKGROUND OF THE INVENTION
THIS invention relates to excavation buckets, and more specifically
to a lip for an excavation bucket.
Excavation buckets such as dragline buckets generally have a lip
welded to the front of the bucket for supporting a plurality of
ground-engaging tools. These lips are usually formed from a single,
rolled steel or cast steel plate with a straight front edge, and
include a plurality of nosepiece castings which are fixed to the
lip so as to project from the front edge of the lip.
Ground-engaging tools are mechanically attached to the nosepieces,
typically by means of adaptor castings.
The castings tend to be relatively heavy and consequently
contribute significantly to the overall mass of the lip. Since the
total mass of a loaded dragline bucket is limited by the dragline
rated suspended load (RSL), it is desirable to reduce the mass of
the bucket so as to allow for an increase in the bucket load and
hence the productivity of the dragline.
A further disadvantage associated with conventional lips for
dragline buckets is that the nosepiece castings have to be welded
to the lip with transverse welds that extend across the upper and
lower surfaces of the lip, and these welds reduce the fatigue
strength of the lip.
SUMMARY OF THE INVENTION
According to the invention there is provided a lip for an
excavation bucket including a lower plate defining a plurality of
integral projections along a front edge thereof, and an upper plate
joined to the lower plate so as to form a laminated structure, the
upper plate defining a plurality of integral projections which
together with the projections on the lower plate form tool
attachment formations in a serrated front edge of the laminated
structure for supporting ground-engaging tools on the lip.
Preferably, at least one additional plate is sandwiched between the
upper plate and the lower plate. In this case, the additional plate
or plates may be designed to project from the upper and lower
plates between adjacent tool attachment formations and may include
apertures for attaching shrouds to the lip between the tool
attachment formations.
Typically, the lip includes one additional plate between the upper
and lower plates, and the additional plate defines openings along
its length for reducing the mass of this plate.
In a particularly preferred embodiment, the projections on the
upper and lower plates are bent out of the planes of these plates
so that the tool attachment formations are inclined relative to the
plane of the lip.
Preferably, the upper plate, the lower plate and the additional
plate are fabricated from rolled steel plate and are subsequently
welded together.
In one arrangement, the lip curves upwardly at each lateral end
thereof so that welds at these lateral ends are located out of
areas of high stress in use.
The invention also extends to an excavation bucket including a lip
as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of
example only, with reference to the accompanying drawings in
which:
FIG. 1 shows a top view of a lip according to the present
invention;
FIG. 2 shows a front view of the lip illustrated in FIG. 1; and
FIG. 3 shows a cross-sectional view along the line 3--3 in FIG.
1.
DESCRIPTION OF AN EMBODIMENT
FIG. 1 of the drawings illustrates a top view of a lip for an
excavation bucket according to the present invention. The lip is
designated generally with the reference numeral 10 and is formed
from three steel plates which are welded together in a manner which
is described in more detail below.
With reference also to FIG. 3 of the accompanying drawings, the
steel plates forming the lip 10 include a lower plate 12, an upper
plate 14 and a central plate 16 which is sandwiched between the
lower and upper plates, as shown. The lower plate and the central
plate are formed from a high strength steel having a minimum yield
strength of 700 N/mm.sup.2, typically WELDOX.TM. 700D, and the
upper plate is formed from an abrasion resistant steel with a
minimum hardness of 40 Rockwell C, typically HARDOX.TM. 400.
The lower plate 12 defines eight integral projections 18 (see FIG.
2) which are formed by cutting recesses into a front edge of this
plate. The projections are inclined downwardly out of the plane of
the plate 12, as shown most clearly in FIG. 3. The upper plate 14
also defines eight integral projections 20 which correspond with
the projections 18 on the lower plate and which are inclined
downwardly out of the plane of the upper plate, as illustrated. To
facilitate the welding of the plates, the peripheral edges of the
upper and lower plates are seen to include bevel surfaces 21.
The central plate 16 includes six openings 22 for reducing the mass
of this plate and is machined so as to accommodate the inclined
projections 20 on the upper plate. Along a front edge of the
central plate 16 eight projections 24 are provided which are
arranged to correspond with the projections 18 and 20, and the
plate 16 defines seven apertures 26 between adjacent projections 24
which are arranged to receive connection pins for securing seven
shrouds to the lip 10. The rear edge 27 of the central plate 16
tapers inwardly, as shown in FIG. 3, to facilitate welding of this
plate to the upper and lower plates.
In this embodiment of the invention, the lip 10 is assembled in the
following manner. First, the three plates 12, 14 and 16 are formed
separately by fabricating three rolled steel plates. During
fabrication, the plates are profiled in a flame-cutting machine,
the central plate is machined as required, and the projections 18
and 20 on the upper and lower plates are bent relative to these
plates. The three plates are then placed one above the other, as
illustrated in FIG. 3, with the central plate sandwiched between
the upper and lower plates, and are pressed together in a press to
ensure proper engagement. Thereafter, the plates are welded
together with welds (not illustrated) that extend along the bevel
surfaces 21 around the periphery of the plates, or at least a
substantial portion of the periphery of the plates, to form a
laminated structure.
The lip formed from the three plates 12, 14 and 16 includes a
serrated front edge 28 which defines eight tool attachment
formations 30 (see FIG. 1) for supporting ground-engaging tools
(not shown). Typically, the ground-engaging tools are welded to the
tool attachment formations as wear elements that can be replaced
when worn.
Seven shrouds (not shown) are then connected to the lip between the
tool attachment formations 30 with connection pins (also not shown)
which are arranged to engage in the apertures 26.
In this embodiment of the invention, the lip is welded to a
dragline bucket but it should be appreciated that the lip could
also be connected to various other types of excavation buckets. In
FIG. 2, the lip 10 is seen to curve upwardly at each side edge
thereof so that lateral edges 32 of the lip can be welded directly
to cheek plates on the dragline bucket out of areas of high stress
in use.
One advantage of the lip according to the embodiment of the
invention described above is that it is relatively light when
compared with conventional lips for dragline buckets. This is
mainly due to the fact that ground-engaging tools are welded
directly to the tool attachment formations and consequently there
is no need for nosepiece castings or adaptor castings which tend to
be fairly heavy. Also, the openings 22 in the central plate 16
serve to reduce the overall mass of the lip. This lip mass
reduction is important because it allows for a larger bucket load
and consequently an increase in the productivity of the
dragline.
A further advantage of the lip of the invention is that there are
no welds on the upper or lower surface of the lip since all of the
welds on the plate 14 extend around the periphery of this plate. In
conventional lips for dragline buckets it is necessary to have
transverse welds on the upper and lower surfaces of the lip in
order to connect the nosepiece castings to the lip. The absence of
these transverse welds on the lip of the invention allows for a lip
with increased fatigue strength.
* * * * *